At the beginning of the circus scene, one of the songs played is the familiar "circus song", Entry of the Gladiators, by Julius Fucik, which wasn't composed until 1897, several years after this supposed time frame.
At about 20:30 into the episode, when Albert asks Laura if she wants his ticket so she can take Almanzo to the circus, you can see flashes of Melissa Gilbert's braces as she responds.